Process and apparatus for drawing sheet-glass.



No. gzms. A PATENTED MAY 29, me.

I. W. COLBURN & E. WASHBURN.

PROCESS AND APPARATUS FOR DRAWING SHEET GLASS.'

APPLIOATION FILED mma, 1905.

i SAHEET-SHEET 1. mg.

FRnTioH COME.

wf? 23m,

No. 821,786. lP'IENNEID MAY 29. 1Q06.

I. W. CQLBRN A; E', WASHBURN. PROCESS AND APPARATUS 'FORSJRAWINS SHEETGLASS.

.APPLIUATION FILED HAR. 3, 1905.

' 4 SHEETS-SHEET 2v Witness@ ,Nm 821,786. 4 PATENTED M'AY 29, 1906.

I. W, COLBURN & E. WASHBURN.

PROCESS AND APPARATUS PQR DRAWING 'SHEET GLASS.

APPMCATIH FILED MAR. s. 1905 4 SHEETS-SHEET 3.

Wimmm No. 821,786. PATHNTED MAYQQ; 1906.

I. w. GOLBURN @L E. WASHBURN..

PROCESS AND APPARATUS FOR DRAWING SHEET GLASS. AEPLIOATIQNVILBDMAR.3,1905.

4 SHEETS-SHEET 4.

uNrr'nn .erafrns rafrnNr ormonrRv'iNe w. ooLBURN AND EDGAR' wAsHBUaN, orFRANKLIN, PENNSYL- i vANiA; snm wAsHBURN AssieNoR To SAID ooLeURN.

endosse ano 'APPARATUS Foa Dmwuae SHEET-GLASS.

Nasamse.

l y `Specification ofLettei-s Batent.

Patented May 29, 1906D 1 Application fil-ed March 3, 1905. Serial No.248,283.

To -1f/ZZ whom it mag/concern:

Beit known that we, Iavnie W. COLBURN and EDGAR WAsHBUnN,of Franklin,Penne Sylvania, have invented a new and useful Process and Apparatus forDrawing Sheet- Glass, which invention is fully set forth in thefollowing'- specificatio'n. [This inventionrelates to the art ofglassworking, and more particularly to the drawing of glass in sheetform from a mass of molten glass. 1

When it is attempted to Idraw a .sheet of glass from a molten massbyinserting' a-bait :therein and slowly .moving the -bait awa provide aprocess and an'apparatus whereby la sheet of glass may be drawn'from amass of moltenglass without narrowing or pulling to .l a thread duringthe drawing operation.

With this object in view the present invention consists particularly inthe process of drawing sheet-glass by preparing a mass of molten glass,drawing a sheet of glass there-l fromI and simultaneously imparting 'anoutward movement tothe surface of said mass` at points adjacent to theedges of the sheet which is being drawn. By outward movement ismeant amovement ofr that portion of the surface ,of tlie glass which isadjacent to the line where the sheet of glass leaves the -molten glass,the movement of the glass being l*away from tl'iecentral portion of thesheet outward-t. c., toward theedge portions of the sheet. This outwardmovement of the surface portion of the molten glass results in a sheetbeing drawn which will remain approximatcly constant in width vor willeven slightly increase in width up to a given dimension asfthe drawingoperation proceeds.' This outward. movement of'the 'surface of themolten glass may be imparted to itin any suitable way. 'One verye'ective means for vplication of heat to said surface.

imparting this 'outward 4movement tothe.

surface of the molten mass consists in immersing two bodies 'ust' belowthesurface of the molten glass an` simultaneously revolving them v1nopposite directions, one with the hands of a clock and theother inl areverse direction. Preferably the bodies which are revolved beneath thesurface of ,the molten .massare 'so near the surface that theirrevolution may cause the glass to slightly rise up or form an undulatingsurface somewhat 'above the-general level of the molten'glass, inv

the receptacle'containing the same. Any suitable form may be given tothe bodies thus revolved lbeneath, the surface of the molten mass. Forthe purpose of illustrating the invention these are herein shown as sim'vple spheres, each operated with a `shaft inclining upward and outwardfrom the receptacle, the power being ap lied to the respec- I tiveshafts in any suita le manner, as by right and left hand worm-gearing.

It' has been found when drawing a sheet of i any extent from a mass ofmolten gl'ass that under some conditions the surface of the molten masshas a tendency tocool or become lowered in temperature to suchan extentas to considerably impair the working condition'of the glass around theouter con- `lines or edges of the receptacle containing the With a viewto overcoming this diffif same. culty the invention further consists indrawing glass in sheet form from a mass of molten glass, whilemaintaining the surface of the molten mass, and particularly vvvthe edgeportions thereof, in working condition by the ape` Various means may beemployed for thus maintaining the temperature of the surface of theglass. `As herein shown this is accomplished by directing a seriesof'jets of flame downe ward against the surface of the molten massadjacent lto the outer edges or limits of the receptacle containing thesame. These .jets

may in some "cases be directed against the surface of the molten massperpendicularly;

but referably each jet of flame has a downwar and outward direction,impinging upon the surfaceof the glass at an acute angle.

This is accomplished by lacing Withinithe v.mouth of the receptac e..containingthel molten glass a gas-conduitprovided Withii,..f

'series of jet-openings directedoutwardlyand downwardly, suchconduitbeing justfabove I the sheet.

- ing the molten glass thereto from a refiningchamberby means ofsuitable conduits. As hereinY shown, there is provided a workingchambveror pot the' working portion of which is separated by a suitablepartition-Wall from ayreceiving-chamber into which the glass isdelivered, as through' a delivery-cpen1ng, by a ladle. This partitionbetween the working chamber and the receiving-.chamber is provided withsuitable openingsfor conduits ads jacent to theopposite ends of theworking chamber, through which the molten glass passes from thereceivingschamber to the working chamber or pot.

. In drawingasheet of glass bythe use of a i bait in the mannercontemplated by the present invention it isv of great importance thatthe sheet of glass as it cools should not crack away from t e bait towhich it is attached.

.- This it is extremely liable to do with baits in the form of sheets ofmet al, such as have heretofore been commonly employed, since thecoefficients of expansion of the glass and the metal cgmposing the baitare widely different. For the purpose of avoiding .this lia- I bilityofthe sheet of glass to crack from the bait` during the drawingoperation there is provided by the present invention a bait composed ofa suitablyysupported plate, to which is attached a coil ef heavyWire,the eneral direction ofthe extension of the coi' being alongthelower ed e of the plate--ie., in the direction ofthe wi th'oi` thesheet. This coil of wire is attached to the plate any suit- .ablemanner, preferably by forming holes or v,openings through the lower ed eof theplate and threading the coil throug these openings. vIt has beenfound that when a bait' of this character has been employed the sheet'ofglass will Y"not crack therefrom during the drawin operation. v

Anot er important consideration` in draw ing sheets of glass from a massof molten glass lies in the fact that the maas should be the 'hotf/statv the bottom, .the heated glass rising to the surface during thedrawing operation. With the object of ifectually accoinplishing thisdesired end thc present invention provides a working pot or receptaclefor molten glass in combination with means for heating the same, theheat being applied most effectively at the bottom portion of the vrecepta 'cle,and particularly at about the'centrai partof the bottomportion. .lhis mana top plan View of that sens ner of applyin the heatis designed more par-v ticularly for t e heating of the mass during thedrawing operation. When it is simply desiredl to maintain the glass inthe working pot or receptacle hot, as over night and between drawingoperations, it is not essential that the iercest heat should be thus atthe bottom, and the present invention thus provides means also forheatingthe massy of molten glass around the sides of the chamber or potto the end that the same may be lmaintained in working condition duringthe intern vals between the drawing'operations. Preferably the heatemployed is that of gas-j ets, and for the purpose of economy the heatemployed to heat the sides of the working chamer or pot between thedrawing operations is of the Bunsen-burner type. i

4In addition to the features indicated above the invention consists inminor details of construction and methods of operation which will bemore specifically hereinafter d escrib ed,

and then 4pointed outin the claims.

It will be understood that the inventive idea involved in theabove-mentioned process may receive various expressions without losingits identity, and a variety of forms of apparatus may be employed inpracticing the process. Moreover, the inventive idea of means anddevices constituting the mechanical art of the invention may receivevarious meciianical expressions 5 one of which is shown in theaccompanying drawings for the purpose of illustrating the invention.Such drawings, however, are for the purpose of illustration only andnotfor the purpose of defining the limits or scope of the invention.

In said drawings, Figure l is a vertical transverse section through theworking chamber or l pot and the heating-furnace surrounding thefurnace, the remaining portions ol the apparatus being shown in frontelevation. Fig. 2 is a vertical section taken at right anglesto Fig. 1on the line 2.2 of said iig-ure. Fig. 3 is portion' df the apparatusshown in Fig. 1 below the bait, the

roo

sheet of glass being shown in horizontal section. Fig. 4 is a pljan viewof the jet-conduit for heating the surface lofthe 'molten glass adjacentto its edges during the drawing' operation.v Fig. 5 isa horizontalsection taken on the line 5 5, Fig. 2. Fig, 6 is a side elevation of abait with a sheet of glass attached thereto.

Referring to the drawings, l is a working chamber or pot surrounded byheating-chamber2, supplied with heat from two sets of burners 3 and 4.0f these-burners the series 3 3 enter the hcati11g-chamberin a planepreicrably just below the bottoirrol' the working chamlmr or pot l, and,as will appear from an inspection ol" Figs. l and 2, they are arrangedin, pairs, so that a jet ol llame directed on one. side will meet a jetof [laine froin-al'lother iet or burner 3 immediately opposite the same,

` ower or ber. it will be understood that the working` eaif/ee .the jetsof flame from the various burners 3 converging -or meeting substantiallyunder the middleof the working chamber or pot.

n the otherhand, the burners 4 are in a plane considerably above thebottom of the.

working chamber and are of the Bunsen type, as indicated at 4, whereprovision is made forthe introduction of air and themixture ofthe samewith tliegas as `igt-proceeds toward the opening of the burner linto theheat- ,iiig-charnber. This vheating-Chamber is proed'with oiftake-flue,which is preferably "arranged to conduct the products of combus-Ation;downward from ai point immediately beneath the Working chamber orpot and has its mouth lor opening surrounded by a raised art 7,-rojecting considerably above the l) ottom portion oftheheating-chamchamber or pot is supported, as upoirpiers 8 8,

within the heating-chamber.

The working chamber or pot is of novel construction, 'the main portionthereof being of oblong rectangular form, its rear side or face,

however, bulgingy outward lconsiderably to form a receiving-chamber fc,having a fillingin openingv y in its top. This bulging or segmentalportidn .of the working pot is divided lfrom the main or opening portionby a partition 9, through the lower portions of which are openings 10.10. (Shown in dotted lines in' Fig. 1 and infull lines in Fig. 2.) .The

working chamber or plot 1 and the receivingchamber 11 are, Wit theexceptiony of this partition. 9, preferably integral.

.'Provisionis made for covering the working chamber or potduring theintervals between the drawing operations and for removing andtransporting the cover to one side 'while the sheetl of glass is beingdrawn. ferring to FigsP2 and 3, 12 12 are rails or ways mounted upon theupperportion' of the su' erstructu're, upon W ich waysacarriage 13 ismounted to travel, which carriage is proa pairvof chains or cables 15,the

sis

"or pot for the l Fortlii purpose of imparting nir-vement to .thesurfare of the molten Iglass in the Working chamber or pot away fromthemedial line ofl the sheet as'it is being drawn means are pro-v videdfor revolving apair of vbodies I'in the to be .the edgesl of t e sheetitsextreme width. These y glass just beneath the surface'v :thereof andat points approxiinatel under' what is designe lwliei'i drawn to`lbodies Ithus revolved beneath the surface of the molten massv may be ofany suitable form for accomplishing the outward movement of themass asthe bodies are slowly revolved in opposite directions.

able refractory material, provided withv shafts 19'19, preferably of thesame material and' As herein shown, thesebodiesare in the form of.spheres 18 18, of suitintegral with the spheres 18. 'These shafts 19`are inclined upwardly and outwardly, preferably at anangle of aboutthirty or thirty-five degreesyfr'om the horizontal, and to accommodatethis upwardand outward inclination'of the shafts 19 the forward side ofthe working chamber `or pot 1 is provided with two outwardly andupwardly flaring lips '2O 20. (See Figs. 2 and 5.) The up- Ward ends ofthe shafts 19 are polygonal in cross-section, these polygonal endsfitting in v corresponding sockets secured to rotate with' 'shafts 2121, which shafts have ontheir outer ends worm-gears 22 22, gearingwithright and left hand worms 23 and. 24 on shaft 25, driven either by crank26 or` by power aplied to pulley 27. (See Fig. 5.) The revoutions of theshaft 25 are such as to slowly dicated by the arrows in' Fig. 1, :andthe spheres being near the surface of the mass of molten glass theirrevolution causes the surface portion of the molten mass to slightlyrise or form an undulation immediately over .the `spheres and slowlymove away from the medial line of the sheet of glass being drawn and inthe direction of the edges of the sheet.

In practicing tliepr'ocess constitutingv a IOC part of the inventionherein any suitable bait and means for moving it outwardly from the massof molten glass may beemployed. Preferably, however, the bait shown inFi s'. 1, 2, andis employed. This bait consistso aplate 28 of anysuitable material, as metal, sus- .lof

pended from a pair of cablesr29 29, passing over a -drum 8() and drivenby any suitable power, 'as by an Evans .friction-cone 3.1. v(Shown inFig. 1.) For the purpose of providing points of attachment for the sheetofl glass to the plate 28 this plate has formed therein near its loweredgea series of holes or perforations 32, and through these holes o rperforati ons a coil of wire is threaded after the manner shownjin, Thiscoil, ifdesired, may be a'regular cylindrical spiral; but preferably theoutline of thecoil in cross-section is such as shown in Figs'.

iio

,Q and 6, wherei in the lower edge or sirleof4 the. coil has fla t-.

'tened, so that "each-spiral forinsa' rounded l point., The sheet'ofglass at the beginning of the operation attaches itselftothe lower or ast'lie sheet. contracts in ,poi`nted portions `of the Vspiral coil anddoes not come .in contact With'fthe plate 28..' The 1 2S `result of thisis that cooling the spirals .of the coil yield, ,sol as to l i 'avoid.placing any .strain upon the 4sheetdue 'y 9 l revolve the spheres 18 18in the direction in- Y i p from a source of fuel-supply, as gas, and 44is l'vided with aburner L'1Sextending in a straight to its contraction,and the cracking of the l glass from the bait is thereby elfectuallyprevented.

lt has been found when drawing a sheet of glass from a massof moltenglass in the manner indicated herein that the surface ofthe moltenglass, and particularly that portion of the surface adjacentl to thewalls of the receiving chamber or pot, becomes cooled. through radiationdue to exposure of the surface during the drawing operation, and thiscooling materially affects the working condition of the molten mass. Forthe purpose of avoiding this cooling of the surface of the i molten massthere is herein provided a means vfor supplying heat directly to theexposed surface, and particularly to that portion of the exposed surfacelying upon the confines or outer edges of the mass of molten glass. Anysuitable means for imparting heat to the surface of the molten massaround its edges or confines may be employed. As herein shown said meansconsists of a conduit or conduits bearing a seriesof gas-jets, whicharev located near the surface of the molten mass and around the edgesthereof, the jets being so positioned as to direct the flame against thesurface of the molten mass, preferably in a downward and outwarddirection, though, if desired, the jets might be directed against thesurface in a practically vertical g' line. Referring to Fig. 4, 43 is apipe leading a ring of pipe connected to 43, the shape of the ring 44being practically that of the inside of the working chamber or pot 1,thoughl somewhat smaller. This pipe 44 is provided with a series ofsmall openings, throughwhieh y the gas passes, these, in effect,constituting a burner provided with a series of jet-openings. As will beunderstood from an inspection of Fig. 4, these jet-openings are formedso as to direct the llame in an outward and downward direction againstthe surface of the molten mass in the working chamber or pot. The pipe43 is connected to the main conduit 45 by a flexible joint 4G, herebythev ring 44 may be raised up out of position when it is l desired toplace the cover 16 over the mass of molten glass in the working chamber.Instead of the ring 44 and a single pipe 4 .il there may be used aplurality of pipes or conduits 47 47, Fig. 3, each connected by flexiblejoints to a main gas-ronduit and each pro line along the sides of theworking (.:lntmber or pot, adjacent to the surface thereof, and providedwith small burner openings, which direct the llame in an outward anddownward direction against the surface of the molten glass, as'isclearly shown in liig. 3.

Operation'. 'lhe glass in the working chamber or pot having been broughtto the proper heat and working condilion and the burners 3 beingigniteihwhilil lln burners/t are turned l saines off, the cover 16 israised f om off the working pot by revolving the drums 14 through theaction of the lever 1'?, and the carriage 13 .is run back upon the waysto the position indicated in Fig. 2. The bait having been lowered so asto permit the power or pointed por-V tions of the wire-coil to becomeimmersed in the mass of molten glass, the burners for heating thesurface of the molten glass being in position, and the gas issuingtherefrom being ignited, the bait is started upward by revolving thedrum 30, and simultaneously with the upward movement of the bait thespheres 18 18 are slowly revolved in the direction indicated by thearrows in Fig. 1, thereby causing the grass onthe surface of the moltenmass to move slowly away from the medial line of the sheet as it drawnand in the direction of the sheets edges. This outward movement of thesurface portion of the molten glass exerts a stretching action upon thesheet in the direction of its edges as the sheet is drawn upward bythebait. i The,

sheet of glass having been drawn to the desired length, the direction ofrevolution of the spheres 18 is reversed, whereupon the sheet of `glasswill rapidly draw to a` thread or rod, which can-be severed by crackingoff or by shears, thereby leaving the molten mass in suitable conditionfor repeating the operation, since the surface is not fouled by massesof broken glass falling thereinto. If desired, the cover lo may then. bereplaced over the working cl amber or pot, and if the drawing operationis no t innnediately repeated and it is only desi red to keep the moltenglass in the working chan'iber or pot in a melted condition the burners3 3, whichhave been in use during the drawing operation, are cut off andthe burners 4 4 are ignited, and by directing their ,iets directlyagainst the sides of the working chamber or pot they serve to keep it inthe desired condition during the interval.

1. 'lhe method of drawing sheet-glass which cons'sts in preparing a massof molten glass, drawing a sheet of glass therefrom, and siinultanemislyimparting movement to the surface portion of the molten mass away fromthe nir-dial line of the sheet and in the direction of the edges of thesheet.

2. 'lhe y method of drawing sheet-glass TOO which consists in rn'eparinga mass of molten i glass, '.lrawing a sheet of glass `therefrorrn andsimultaneously imparting movement to the surface portion of the moltenmass in oppir posite direi-,tions away from the medial line of the sheetand in the direction of the edges of the sheet.

Il. 'lhe method of drawing sheet-glass which consists in preparing amass of molten glass, drawing a sheet Vof glass therefrom, simultaneousl\v imparting movement. to the surface portion of lhe mollen mass inopposite directions away from the medial line and v glass, means fordrawing a sheetof glass therefrom, and means imparting movement to thesupplying heat to thelsurface of said molten toward the edges of thesheet, and imparting l heat to the surface of the molten massen opiposite sides of the sheet.

4. The method of drawing sheet glass which consists in preparing a massof molten glass, drawing a sheet of glass therefrom while the surfaceportion of the mass adjacent to said sheet is kept moving away from themedial line of the sheet toward its edges, and

mass.

5. The method lof drawing sheet glass which consists in preparing a massof molten glass, and drawing a sheet of glass therefrom while thesurface portion of said mass is kept moving away from the medial line ofthe sheet toward the edges.

6. In glassdrawing apparatus, the combination of a receptacle containingmolten glass, means for drawing a sheet of glass therefrom, and meansmoving the surface portion of the molten glass away from the medial lineof the sheet toward its edges. y

7. In glassdrawing apparatus, the combination of a receptacle containingmolten ,surface portion of said molten glass in opposite directions fromthe middle thereof.

'8. In glass-drawing apparatus, the combination of a receptaclecontaining a mass of molten glass, means for drawing a sheet of glasstherefrom, and means within said mass for stretching lsaid sheet asdrawn.

9. In glass-drawing apparatus, the combination of a receptaclecontaining a mass of`V molten glass, means for drawing a sheet of glasstherefrom, anda plurality of revolving Y bodies beneath the surface ofsaid mass.

10. In glass-drawing apparatus, the coinbination of a receptaclecontaining a mass of molten glass, means for drawing a sheet of glasstherefrom, and a plurality of bodies rcvolving in oppositev directionsbeneath the surface vof said mass. h

11. Inglass-drawing apparatus, the cornbination ofa receptaclecontaining a mass of molten glass, .two revolving bodies beneath the.surface of the mass, and means for drawing a sheet of glass from thesaid inassbetween said bodies.

12. In glass-drawing apparatus, the coinbination of a receptaclecontaining a mass of molten glass, two spherical bodies rcvolublc inopposite directions beneath the surface of said mass, means forrevolving said bodies, and means for drawing a sheet of glass from themass bet-Ween said bodies.

13. In an apparatus for drawing sheetglass, the combination of areceptacle containing a mass of molten glass, means for drawing a sheetof glass therefrom, means for imparti-ng heat vto the bottom of saidmass of molten glass, and means located below the surface of the massand acting to impart motion to said surface away from the medial line ofthe sheet and toward its edges during the drawing operation.

14. In apparatus for drawing sheet-glass, the combination of areceptacle containing a mass of molten. glass, means for ldrawing asheet of glass therefrom, means for heating said mass of molten glass atits bottom, means forheatiiig the upper surface of said mass during thedrawing operation, and means located below the surface of said moltenmasa and imparting an outward movement to the surface of the mass fromthe medial line of the sheet toward its edges.

15. In an apparatus for drawing sheetglass, the combination of areceptacle con.- taining a mass of molten glass, means for drawingasheet of glass therefrom, two bodies located beneath the surface ofsaid mass adjacent to the edges of the sheet drawn, and means forrevoijving said bodies in opposite directions.

16. In an apparatus for drawing sheetglass, the combination of areceptacle containing a mass of molten glass,.means for drawing a sheetof glass therefrom, two spheres located beneath the surface of said massand adjacent to the edges of the sheet being drawn, and means revolvingsaid spheres in opposite directions during the drawing operation.

17. In apparatus for drawing sheet-glass, the combination of areceptacle containing a mass of molten glass, a plurality of burners theflames from which converge to a common oint under said receptacle, meansfor drawing a' sheet of glass from said mass, and abuiner directing jetsof llame in a downward and outward direction. upon the surface of saidmass von opposite sides of the sheet as drawn.

18. In apparatus for drawing sheet-glass, a receptacle containing a massof niolten glass,

means for drawing a sheet of glass therefrom,

and a burner surrounding said sheet and directing jets of llame in adownward and outward direction upon the surface of said mass during thedrawing ojniration.

'19. In an apparatus for drawing sheetglass, the combination of areceptacle containing a mass of molten glass, means for drawing a sheetof glass therefrom one of the Walls of said receptacle having a pair ofupwardly and outwardly inclined lips, aA pair of upwardly and outwardlyinclined shafts rcvolving in saidlips and a pair of revolublc bodiesoperatively connected to said shafts below the surface of said moltenmass.

20. in an apparatus for drawing sheetglass, the combination 'of areceptacle containing a mass of molten glass, and a bait for drawing asheet ofglass tbcrcfron'i, said bait consisting of a plate having ahorizontallydisposed metallic coil secured thereto.

21. ln apjniratusl'ordrawing sheet-glass,a

IOO

IOS

IIO

receptacle containing a mass of molten lass, a halt for drawing a sheetof lass there om, said bait consisting of a meta lic plate havinga'horizontally-disposed coil of wire secured thereto, and' means foroperating said bait.

22. In apparatus for drawing sheet-glass, a receptacle containing a massof molten a bait for drawing a sheet of glass there om, said baitconsisting of a plate having a series of holes along its lower ed e; anda coil of wire threaded through said holes, and means for operating saidbait.

23. `In an a -aratus for drawing sheetglass, the com mation of areceptacle containing a mass of molten glass, a pair of inelined shaftsoperatively connected to two revoluble bodies beneaththe surface of saidmass and having worm-gears on their outer lass,

ends, a right and lefthand worm engagin said gears, and means forvoperating sai worm. v

24. In glass-drawing apparatus', thecornbination of a receptaclecontaining a mass of molten glass, from, and means moving Within saidmass for cunteracting the narrowingtendenoy of the s eet.

means for drawing a sheet there- In testimony whereof` we have signedthis specification in the 111g witnesses.

`IRVING W. ooLisURN. EDGARl WASHBURN Witnessesz` y I FRANCES' L. KING,

J. H. OsM'ER.

presence of two. subserib-

